They usually step up to the plate and do the right thing, but it sometimes takes some prodding on unusual stuff. I had an issue when I stepped up my GTX260 to a GTX285 upon release. The card that showed up was a 260 with a dead fan in a GTX285 box, but with matching serial numbers on the box and card meaning someone in their packaging dept. made a switcheroo and got themselves a new card. After a couple of phone calls and a few emails, they finally agreed to cross-ship a replacement card as long as I gave a Visa number in case the old card didn't come back to them. As I recall, they sent the new GTX285 with 2 day service from California, which eased some of the pain.

TLDR version; they've still got decent CS in my books. When I had to RMA a X58 board last year it was pretty painless.